<template>
  <div class="s-canvas">
    <canvas
      id="s-canvas"
      :width="contentWidth"
      :height="contentHeight"
    ></canvas>
  </div>
</template>

<script setup>
import { onMounted, watch } from 'vue';


const props = defineProps({
  identifyCode: {
    // 默认注册码
    type: String,
    default: "A2sa8",
  },
  fontSizeMin: {
    // 字体最小值
    type: Number,
    default: 25,
  },
  fontSizeMax: {
    // 字体最大值
    type: Number,
    default: 35,
  },
  backgroundColorMin: {
    // 验证码图片背景色最小值
    type: Number,
    default: 200,
  },
  backgroundColorMax: {
    // 验证码图片背景色最大值
    type: Number,
    default: 220,
  },
  dotColorMin: {
    // 背景干扰点最小值
    type: Number,
    default: 60,
  },
  dotColorMax: {
    // 背景干扰点最大值
    type: Number,
    default: 120,
  },
  contentWidth: {
    // 容器宽度
    type: Number,
    default: 90,
  },
  contentHeight: {
    // 容器高度
    type: Number,
    default: 32,
  },
})

// 生成一个随机数
const randomNum = (min, max) => {
  return Math.floor(Math.random() * (max - min) + min);
}

// 生成一个随机的颜色
const randomColor = (min, max) => {
  let r = randomNum(min, max);
  let g = randomNum(min, max);
  let b = randomNum(min, max);
  return "rgb(" + r + "," + g + "," + b + ")";
}
//画图
const drawPic = () => {
  let canvas = document.getElementById("s-canvas");
  //创建一个2D对象作为上下文。
  let ctx = canvas.getContext("2d");
  ctx.textBaseline = "bottom";
  // 绘制背景
  ctx.fillStyle = "#e6ecfd";
  ctx.fillRect(0, 0, props.contentWidth, props.contentHeight);
  // 绘制文字
  for (let i = 0; i < props.identifyCode.length; i++) {
    drawText(ctx, props.identifyCode[i], i);
  }
  drawLine(ctx);
  drawDot(ctx);
}
//在画布上显示数据
const drawText = (ctx, txt, i) => {
  ctx.fillStyle = randomColor(50, 160); // 随机生成字体颜色
  ctx.font =
    randomNum(props.fontSizeMin, props.fontSizeMax) + "px SimHei"; // 随机生成字体大小
  let x = (i + 1) * (props.contentWidth / (props.identifyCode.length + 1)) - 8;
  let y = randomNum(props.fontSizeMax, props.contentHeight - 5);
  var deg = randomNum(-30, 30);
  // 修改坐标原点和旋转角度
  ctx.translate(x, y);
  ctx.rotate((deg * Math.PI) / 180);
  ctx.fillText(txt, 0, 0);
  // 恢复坐标原点和旋转角度
  ctx.rotate((-deg * Math.PI) / 180);
  ctx.translate(-x, -y);
}

// 绘制干扰线
const drawLine = (ctx) => {
  for (let i = 0; i < 4; i++) {
    ctx.strokeStyle = randomColor(100, 200);
    ctx.beginPath();
    ctx.moveTo(
      randomNum(0, props.contentWidth),
      randomNum(0, props.contentHeight)
    );
    ctx.lineTo(
      randomNum(0, props.contentWidth),
      randomNum(0, props.contentHeight)
    );
    ctx.stroke();
  }
}

// 绘制干扰点
const drawDot = (ctx) => {
  for (let i = 0; i < 30; i++) {
    ctx.fillStyle = randomColor(0, 255);
    ctx.beginPath();
    ctx.arc(
      randomNum(0, props.contentWidth),
      randomNum(0, props.contentHeight),
      1,
      0,
      2 * Math.PI
    );
    ctx.fill();
  }
}

onMounted(() => {
  drawPic()
})

watch(() => props.identifyCode, (New, Old) => {
  drawPic()
})

</script>

<style lang="less" scoped>
@import "./index.less";
</style>